The present invention relates to time varying identification badges, and more particularly, to a reusable badge system with a programmable memory.
The necessity of discriminating between authorized and unauthorized persons has generated the widespread use of identification systems for control of access to secure areas or facilities. Existing identification systems typically use a badge with some method of uniquely associating the badge with the individual wearing it. These methods include photographs, signatures, finger prints, etc. The unauthorized use of such security badges can become a problem, especially where large numbers of people are involved, or where there is high turnover, so that individual recognition cannot be relied upon.
There have been attempts to overcome the limits of these systems which may be easily counterfeited. U.S. Pat. No. 4,542,982 discloses a method for making badges which vary with time by employing a light sensitive badge which changes color after a specified period of time thereby blocking out validating information. The badge generated by this system is discarded after the preset exposure time has elapsed.
An electroluminescent badge used for promotional and display purposes is disclosed in U.S. Pat. No. 4,637,148. Although not used for security identification, this patent does recite the use of an electrically illuminated panel worn as a badge in which the illumination can be periodically interrupted.
Liquid crystal displays have been developed for a number of applications where the use of a miniaturized display instrument is preferable to using traditional cathode ray tubes. Wrist watches and calculators are common examples of the use of liquid crystal displays. See for example, U.S. Pat. No. 4,352,102, and the references cited therein.